[qutebrowser] Per-domain editor.command, or equivalent

[David Nebauer]

Excerpts from Florian Bruhin's message of January 6, 2019 4:18 pm:
> I'm not sure actually. Is there other use-cases you can think of apart
> from setting the file type?

I personally can't. But then, it's not something I've devoted a lot of 
thought to. It does seem to me there is more customisation possible with 
this setting compared to per-domain setting of the file extension. I 
cannot say, though, whether that translates into any real world 
applications.

> If it's only for that, I'd strongly prefer a (per-domain) setting to set
> the filename extension for the file getting opened:
> https://github.com/qutebrowser/qutebrowser/issues/2727
> 
> Because then that'd work for any editor, not just vim.

This would also completely address my use case. I vote for whichever is 
more likely to be implemented first :)

-David